Disposable personal care absorbent articles are traditionally manufactured from a variety of fabrics, often nonwoven materials, that are delivered to manufacturing facilities on rolls for conversion into product. Many of these fabrics are the fluid intake materials of the articles. For the purposes of this application, the term “fluid intake” shall refer to those layers in an absorbent article through which fluid passes after being excreted from a user, as it travels to the primary fluid retention materials (sometimes referred to as the absorbent core) of the absorbent article. The term “fluid intake” does not encompass the primary fluid retention materials (such as for example superabsorbent materials and substantially cellulosic layers). A variety of fluid intake fabrics are often included in personal care product structures because they each offer particular functional benefits to the overall product. For example, some fluid intake materials may be more suitable as topsheet or liner layers that provide initial contact with the skin of a user, while others may better serve as fluid transfer or surge layers within the interior of a layered product. The term “surge layer” is so called because it assists in the control of surges of fluids, such as urine or menses, delivered by the wearer of the absorbent article that might result in leakage, if not for the surge layer. Still further, some materials may be best suited as absorbent core-encasing layers (or core wrap materials), allowing fluid to pass through into the fluid retaining absorbent core, but preventing components from within the absorbent core layer from leaking out of the product.
As a result of the wide variety of fabrics used for these disparate purposes, problems have been encountered in bringing these diverse fabrics together on a production line. Some of these functionally diverse fabrics are derived from relatively slow and inefficient manufacturing processes. Other materials are produced from extremely small diameter polymeric fibrous webs so as to trap particulates, and present manufacturing and cost challenges. Still other fabrics are produced at relatively higher basis weights than would normally be needed for adequate functionality, in order to allow for the high speed of unwinding and handling during conversion into product. For example, materials of a certain basis weight that could be satisfactory for use within a product, may be too delicate to withstand processing steps.
As a result of such material conversion needs, product conversion processes are often overloaded with the integration of specialized material layers, some of which overcompensate to accommodate the rigors of high-speed, multi-step manufacturing systems. As an example, fabric properties, such as thickness and density may change once wound on a storage roll. In order to provide for a desired final thickness and density in a converted product, a fabric layer may be manufactured at a certain pre-conversion specification, taking into account the changes which will eventually occur to the fabric once wound on, and unwound from a storage roll, and exposed to further processing. A need therefore exists for efficiently produced fluid intake materials which can handle the rigors of a product converting process.
The lamination of separately produced fluid intake layers also leads to inter-layer connectivity issues. For example, spatial gaps may exist between layers, thereby impacting fluid movement as it travels to a core layer. Adhesive (typically hydrophobic) between separately produced fluid intake layers may also impact fluid flow and result in a stiffer product. Such obstacles to fluid flow frequently hamper the rapid transition of fluid from one layer to the next. Therefore, a continuing need exists for absorbent articles with fewer fabric layers, and with fabric layers having more efficiently designed features/properties including a reduced mass, tighter connectivity, and lack of reliance on separate adhesive layers for bonding. Such efficiency would result in cost savings as well. Absorbent core layers in personal care absorbent articles often include small particles, such as superabsorbent polymer (SAP) particles, to enhance absorbent capacity of the articles. Such core layers are often enveloped by separate core wraps of cellulosic tissue or polymeric nonwoven materials. Such nonwoven materials often include small diameter fibers (meltblown fibers) so as to prevent the migration of the small SAP particles out of the articles. Attempts have been made to design core layer structures with modified wrapping. However, such wrapping often results in additional mass in the products, additional adhesive layers, and subsequently additional production costs. A need therefore exists for core wrap functionality in a product, with reduced mass and adhesive costs.
Attempts have been made to produce unitary absorbent fabrics that combine the features of what has been traditionally employed in multiple layers of absorbent material. Such unitary fabrics have resulted in only modest improvements in fluid handling behavior with thicknesses and fabric weights equal to or greater than the combined weight of the original absorbent layers traditionally used in such absorbent products. Most often, such unitary absorbent fabrics have resulted in less desired functionality than what would have been available through separate individual layers.
Obtaining additional functional performance often necessitates additional fabric layers or basis weights. Such additional layers and basis weight would typically add further cost and manufacturing challenges to converting systems. Without fabric mass reduction or added functional benefits, the development of unitary structures would not justify such conversion inefficiencies. A need therefore exists for such reduced mass fabrics that continue to provide the same or better functional expectations as previously utilized multi-layered fabrics, but at lower costs. Further, a need exists for such fabrics that could provide for multiple functionality, and which could be produced by simplified manufacturing systems. A need also exists for manufacturing processes that would reduce the amount of material integration steps needed to produce a personal care absorbent article.